The present invention relates to refrigeration compressors. More specifically, the field of the invention is that of lubrication systems for the connecting rod, piston, and wrist pin of a hermetic compressor.
One problem of conventional compressors involves the piston-connecting rod assembly, and particularly the pistons, absorbing heat while compressing the refrigerant fluid. The residual heat of the piston can cause inefficiencies in the compression process and can lead to compressor failure. However, difficulty exists in cooling the connecting rods, wrist pins, and pistons because of the small amount of space available inside the compressor for cooling. Lubricating fluid is often used for the dual purpose of lubricating and cooling the crankcase assembly. However, the limited amount of space available for the lubrication system hinders its ability to satisfactorily cool the crankcase.
One prior art arrangement includes a connecting rod having a lubricating window for allowing lubricant to spray out of a passage of the crankshaft when aligned with the window. This arrangement causes a continuous oil spray toward the piston while the passage is aligned with the window. The crown of the piston absorbs the most heat, therefore cooling the crown is essential. Although the oil spray is aimed to impinge on the piston, often insufficient oil pressure causes some of the oil to miss the piston crown, hitting other less critical parts of the compressor. As cooling the crown of the piston and its associated parts is advantageous, the prior art lubrication systems for the connecting rod, wrist pin, and piston impair efficiency because they fail to reliably cool those critical parts.
What is needed is a lubrication system for the connecting rod, wrist pin, and piston which adequately cools while providing adequate lubrication for the compressor.